A wide variety of printers record images on receiver medium such as paper, fabrics, or films that are specially treated at least one side in order to facilitate the formation of images thereon or to provide enhanced stability of an image printer thereon. In some of these printers, such receiver mediums are provided in roll form with the receiver medium being rolled with the treated side facing outward. This arrangement enables the components of a printer that uses such a rolled receiver medium to be arranged in relatively compact form factor. However, this creates a risk that the specially treated side will be brought into contact with the hands of an operator when manipulation of the receiver medium is necessary, such as to load receiver medium or to clear jams. Further, it will be appreciated that during loading of the receiver medium or at various times during the use of such a rolled receiver medium, there exists a risk that contaminants will be released and will contact the specially treated surface of the receiver medium. Such manual or contaminant contact can have deleterious effects on the receiver medium, including but not limited to altering the distribution or concentration of treated materials on the treated surface, introducing contaminates on the treated side or by compressing, reshaping, stretching, creasing, or tearing the receiver medium.
Where contact causes such deleterious effects it can be difficult to provide a printed image having an appropriate appearance using the affected receiver medium. Further, where a receiver medium that is torn, stretched, or contaminated as a result of contact, the use of such receiver medium can seriously interrupt the use of the printer by contaminating a series of subsequent printing operations or by ripping, tearing or otherwise failing in a manner that interferes with the flow of receiver medium through the printer or with other operations of the printer.
One possible approach to addressing this problem is to use special packaging materials to package rolled medium so that a user can load a rolled medium, without directly touching the medium. For example, U.S. Pat. No. 5,839,839, entitled “INK FILM REFILL FOR HEAT-TRANSFER PRINTER” filed on Jan. 31, 1997 by Brot et al. describes a removable wrapping that is applied around a rolled donor medium at the time of manufacture. This wrapping is shaped and positioned so that it covers areas of the receiver medium that are likely to be contacted during loading. In some instances, the wrapping contains printed instructions that illustrate or describe a loading process that a user is to use that will only require manipulation of the wrapped portion of the receiver medium. After loading, the wrapping is discarded.
However, it will be appreciated that this approach merely provides protection for the rolled medium during an initial loading process. However, this does not protect the receiver medium against deleterious effects caused by manual or contaminant contact with the receiver medium at any time after the receiver medium is loaded. For example, the approach of the '839 patent is ineffectual when it may be necessary or desirable for a user to remove and reload rolled medium such as to clear paper jams or to switch from one type of receiver medium to another type receiver medium. Similarly, the approach of the '839 patent does not protect the rolled medium from contamination that contact can occur after loading of the rolled medium.
Another approach has been to preprogram printers that use rolled receiver medium to discard a predetermined length of such receiver medium upon loading. One example of a prior art printer 10 of this type is illustrated in FIG. 1. As is illustrated in FIG. 1, when an unused roll 14a of receiver medium 12 is loaded, prior art printer 10 advances receiver medium 12 by a predetermined length. In this illustration, the predetermined length is equivalent to six printable image frames 16a-16f. Typically, this predetermined length is intended to be long enough so that when unused roll 14a of receiver medium 12 is loaded into prior art printer 10, a length equal to an entire circumferential length of unused roll 14a of receiver medium 12 is discarded. This approach avoids the use of potentially contacted receiver medium 12 by discarding an outermost layer of receiver medium 12 and allowing use of other layers that were effectively wrapped by the outermost layer at the time of the potential contact.
While this approach is useful and simple to implement, it can be wasteful when a used roll 14b of receiver medium is reloaded into prior art printer 10 as may occur during printer maintenance or as may occur when a user wishes to use different types of receiver medium.
FIG. 2 illustrates an example of how this waste can occur. As illustrated in FIG. 2, used roll 14b of receiver medium 12 has a circumference 18b, that is substantially smaller than the circumference 18a of the unused roll 14a of receiver medium 12. The length of receiver medium 12 that may be subject to contact during loading or reloading is smaller than the length of receiver medium 12 that may be subject to contact if an unused roll 14a of receiver medium 12 had been located in printer 20. However, the prior art printer 10 discards the same length L of receiver medium 12, including in this example, six image frames 16a-16f. Thus, such a prior art printer 10 discards excess receiver medium. In printers such as thermal printers where donor ribbon and receiver medium are sold in matched combinations, this can cause user of the prior art printer 10 to have an apparent excess of donor ribbon after receiver medium 12 is exhausted. This can lead such users to assume that they have not been provided with the appropriate amounts of receiver medium 12, which in turn, can lead to user dissatisfaction.
What is needed therefore is a method for operating a printer that minimizes the potential risks imposed by the use of receiver medium that has potentially been compromised through manual or contaminant contacts.